1. Field of the Invention
This invention relates to an apparatus for and method of controlling ignition of a general-purpose internal combustion engine.
2. Description of the Related Art
Many of four-cycle general-purpose internal combustion engines are configured to produce ignition signals, in addition to in the compression stroke, also in the exhaust stroke among the intake, compression, expansion and exhaust strokes so as to simplify the structure, and based on the ignition signals, conduct the ignition. The ignition based on the ignition signal produced in the compression stroke is called a “normal ignition” because it is conducted in accordance with the combustion cycle to burn air-fuel mixture, while the ignition based on the ignition signal produced in the exhaust stroke is a “waste ignition” because it is the ignition not required and the air-fuel mixture is not burned.
Such the configuration disadvantageously shortens the duration life of an ignition plug of the engine due to the waste ignition. Since this disadvantage is caused by generation of two ignition signals per one rotation of a crankshaft, it may be configured to produce the ignition signal resulting only in the normal ignition by providing a reluctor and pulser on a camshaft whose half rotation corresponds to one rotation of the crankshaft.
Further, Japanese Patent No. 3582800 proposes a technique to use a second pulse signal produced at every unit rotation angle of the crankshaft in addition to a pulse signal produced at every rotation thereof so as to determine whether the pulse signal outputted at every rotation is produced in the compression stroke or exhaust stroke and conduct the ignition based on the pulse signal produced in the compression stroke.